In an information processing device, a communication processing device, and an information processing system including a server device, for example, predetermined packets are repetitively transmitted to the server device through the communication processing device from the information processing device such as a home PC (Personal Computer) or electronic equipments (for example, WO 2004/030292). Here, the communication processing device is a router having, for example, NAT (Network Address Translation) function. One purpose in which the information processing device repetitively transmits the packets to the server device is to maintain a port of the communication processing device, and the other purpose is to perform a prescribed process in the server device.
First, the maintenance of the port of the communication will be described. In the communication processing device having the NAT function such as a router, when the packets are transmitted to the side of WAN (Wide Area Network) from the side of LAN (Local Area Network), a private IP address and a port number of the side of LAN are converted into a global IP address and a port number of the side of WAN. In addition, when the packets are received at the side of WAN, a filter process is performed by a predetermined receive filter rule, and the inverse conversion of an address conversion is executed, thereby sending the packets to the information processing device. At this time, a receive filter rule determines a receiving possibility of the packets from the side of WAN with respect to the port in which the packets are transmitted from the side of LAN of NAT. Moreover, and the receive filter rule includes an address sensitive filter that receives the packets from only an address transmitting the packets from the port, a Port Sensitive filter that receives the packets from only a port transmitting the packets from the port, and a No Filter having no filter. Time is set in the communication processing device, and the time performs such address conversion. More specifically, after a prescribed period has elapsed since a certain address conversion was lastly performed between the side of WAN and the side of LAN, the address conversion of the packets received from the side of WAN is not performed, but the address conversion of the packets received from the side of LAN is newly performed. That is, since the packets from the side of WAN are not received in the information processing device, it is inaccessible from an external device such as a cellular phone to the information processing device through the server device. The prescribed period will be called a port maintaining time. Accordingly, to maintain the port of the communication processing device so as to be accessible from the external device such as a cellular phone to the information processing device through the server device, that is, such that the packets from the side of WAN are transmitted to the information processing device through the server device, the packets are repetitively transmitted.
Next, a prescribed process of the packets to be repetitively transmitted, which performs in the server, will be described. For example, the prescribed process in the server is a process that is to know whether or not IP address at the side of WAN of the communication processing device is changed. The IP address at the side of WAN of the communication processing device may be modified every a prescribed period by a setting of a connection provider or the like. In such case, when the server device does not know the change of the address, the server device does not transmit information to the information processing device through the communication processing device. As a result, it is inaccessible from the external device such as a cellular phone to the information processing device through the server device. Accordingly, the packets are repetitively transmitted such that the server device knows the change of the address of the communication processing device.
However, when the server device accepts the packets to be repetitively and frequently transmitted, there is a problem that a processing burden on the server device increases that much. Especially, when the port maintaining time of the communication processing device having NAT function to which the information processing device is connected is short, the problem becomes remarkable. In addition, generally, since the packets are repetitively transmitted from plural information processing devices to one server device, the processing burden on the server device is increased that much.